It is known in the art of elevators to monitor the number of people entering and leaving elevators for a short period, e.g., during the course of a typical day and to use such information to create more effective dispatching strategies or to plan for modernization projects.
In contrast to various automatic control devices usually intended for permanent installation, the most widespread and effective method utilized in the prior art for short term passenger tracking has been to station a person in each car to record the movement of people in terms of numbers, time and floor by hand. This is a laborious process which tends to be error prone. Motion sickness can also become a problem after a period of monitoring, requiring a sizeable number of relief personnel. It would thus be advantageous to have an accurate portable device to perform this function.
As suggested, there are already known various arrangements for automatically detecting penetration of humans into or movement through a controlled region. Such detecting arrangements are being used, for example, to defend a perimeter of an installation, to monitor movement of personnel within an installation, to detect the presence of people on premises or the like.
Various arrangements of detectors and recordal devices have been tried for various purposes but these suffer from inaccuracies. So, for instance, U.S. Pat. No. 3,207,266 discloses an elevator passenger counting and totalizing device in which a pair of preferably infrared horizontal beams traverse the entranceway of an elevator car which when interrupted actuate suitable circuitry to give an indication of a number of people entering and leaving the car.
Also, for instance, U.S. Pat. No. 4,263,585 discloses an intrusion detection system in which a multi-segment mirror focuses thermal radiation emanating from a moving person onto a thermopile detector in such a manner that each mirror segment separately directs the radiation in succession to detector elements, whereby the direction of movement of such a person can be determined.
Another device responsive to infrared radiation is disclosed in U.S. Pat. No. 4,346,427, wherein an infrared sensor is being used to detect any movement of a person into or within the region under surveillance The output signal of this sensor is utilized for controlling the operation of lights, air conditioning or the like for the affected region. A control device of this type is also disclosed in the published international patent application No. PCT/US81/01769 (International Publication No. WO82/02270). Moreover, a passive infrared occupancy detector of a similar type has been developed by Tishman Research Co. and United Technologies Corporation and is commercially available under the designation Infracon Model 628.
U.S. Pat. No. 4,023,135 to Hanmura et al discloses an ultrasonic device, using pulse echo techniques, for counting people as they enter the lobby or car.
Two optical systems which scan the perimeter of an area are covered in U.S. Pat. Nos. 4,127,766 (to Thayer) and 4,303,851 (to Mottier). Thayer teaches using an array of discrete optical sensors whereas Mottier teaches using a line scan camera.
Other systems have used microwave doppler radar for passenger counting purposes. See U.S. Pat. No. 4,317,117 (to Chasek) and G.B. Patent No. 2072987.
Monitoring hall calls, load sensing and floor mats have also been used for passenger counting purposes. See U.S. Pat. Nos. 4,458,788 (Traffic Analysis Apparatus for Lift System, to Lepore), 4,492,288 (Group Control for Elevators Containing an Apparatus for Controlling the Down-Peak Traffic, to Schroder), 4,299,309 (Empty Elevator Car Determination, to Bittar et al), and 3,543,883 (Floor Mat Passenger Counter, to Kozera).
From another approach, various attempts have already been made to develop techniques for measuring or estimating the elevator load, such as weight-measuring sensors mounted on the elevator. Thus, a system for measuring interfloor traffic for group control of elevator cars is disclosed by Yoneda in U.S. Pat. No. 4,536,842 where the number of incoming and outgoing passengers at an elevator floor is determined by detecting a change in weight of the elevator car assuming that one passenger weighs 55 to 60 kg. However, since equipment of this type is sensitive only to the total weight of the elevator occupants and not to their number, this equipment is not capable of distinguishing between the presence in the elevator of, say, on the one hand, one elevator user who is rather heavy, and on the other hand, two or three elevator users who are individually much lighter. Thus, this equipment does not provide reliable information about the actual number of elevator occupants or about the actual number of people entering or leaving the elevator at the particular floors.
As advantageous as the above devices may be for the purposes for which they have been developed, they are actually not as well suited as might be desired for accurately determining the number of people passing through the region under surveillance, such as an elevator doorway, and the direction of passage of such people through the surveillance region.
Furthermore, in general, these approaches are not suitable for short term monitoring of elevator passenger traffic for a variety of reasons. The microwave, optical and ultrasonic techniques are either difficult to temporarily install in an elevator car or would not be sufficiently precise to accurately (i.e., less than 5% error) count passengers. Techniques using hall calls or load sensing require interconnection with the elevator controller which is not always practicable.
As discussed above, in many instances, it would be desirable to possess accurate information so as to be able to use it for various purposes, such as for determining the number of people present in an elevator in order to estimate the elevator load, for determining the number of people entering and leaving an elevator at any of the various floors of a building to determine the traffic flow pattern in the building for use in elevator dispatching, or the like.
As also discussed previously above, heretofore in the art, accurate collection devices have not been made. The lack of accuracy of the information and the cost of gathering this information outweigh any benefits derived therefrom. Thus, the prior art approaches leave much to be desired, especially as far as the accuracy or veracity of the information gathered.
While it will be desirable for some applications to use an accurate counting scheme as a permanent part of the control apparatus for an elevator or other installation, it will also be advantageous to be able to simply and independently monitor an installation for a relatively short period of time such as a day in order gather the information and use it, for example, to modify an elevator dispatching control strategy or to plan for modernization projects.